How to find out why the computer freezes?

Question

Windows

I rolled it into a toy, used ALT-TAB, Google Chrome stopped responding and the taskbar hung, the system costs a year, there were no complaints. It was possible to al-tabnutsya on Skype, a toy, and somewhere else. Repeated more than once, only reboot saves. How can I find out what it is, or maybe someone has come across this and have a solution?
Computer Configuration:
OC: Windows 7
CPU: Intel core i7 4790(box)
GPU: Nvidia gtx460
RAN: 8.00GB Dual Channel DDR3
HDD: 931GB Western Digital WDC WD10EZEX-08M2NA0
SSD: 59GB TS64GSSD340 ATA Device (SSD)

Answer 1

I do not understand, the computer is frozen tightly?
1. Is the mouse crawling/not crawling?
2. Does the NumLook lamp not respond to the NumLook key?
3. Is the HDD light on / off / blinking?
If everything is NO - most likely overheating, cleaning is needed.